Heathrow Airport has unveiled a £21 billion proposal to construct a third runway within the next decade, aiming to significantly boost its flight capacity.

The expansion plans include the development of new terminal capacity to accommodate 150 million passengers annually, a substantial increase from the current 84 million.

The proposed runway, measuring 3,500 meters, would be situated to the north-west of the existing airport, allowing for an increase in annual flights from 480,000 to 756,000.

However, the project faces opposition from environmentalists who raise concerns about carbon emissions and noise pollution, urging the government to reconsider the expansion.

Supporters, including business groups and unions, argue that the expansion will enhance market access and create jobs, despite the environmental concerns raised.

London Mayor Sir Sadiq Khan has voiced his opposition to the runway, citing its potential negative impact on residents, while the government maintains that the expansion is vital for connectivity and economic growth.

Conservative shadow transport secretary Richard Holden has emphasized that the project should be privately funded without taxpayer support, advocating for accountability in infrastructure development.

Heathrow has pledged to achieve net zero carbon emissions by 2050 and reduce its noise footprint, although critics remain skeptical about the expansion's alignment with climate goals.

Heathrow's CEO, Thomas Woldbye, has stressed the urgency of the expansion, highlighting its importance for trade and connectivity, and indicating readiness to invest pending government approval.

The UK government is currently reviewing the runway proposal, with a decision expected in early autumn 2025, which will also consider alternative plans from the Arora Group.

While the expansion promises economic benefits such as job creation and lower fares, it also raises concerns about increased noise, air pollution, and significant local disruption due to construction.

The expansion will necessitate the demolition of 752 homes, with compensation offered to affected homeowners as part of the project.